Looking Up: Spring time is open galaxy season

Friday

May 19, 2017 at 12:43 PMMay 19, 2017 at 1:03 PM

Peter BeckerMore Content Now

At this time of year — spring in the northern hemisphere- we face outward up (down?) away from the plane of the Milky Way Galaxy, straight out where the view has the least cosmic dust. The Milky Way, remember, is generally flat like a buttermilk pancake, although with a glob of butter (margarine?) right in the middle- and on either side. The dabs of butter here refer to the thick central hub of our galaxy. The “pancake” is actually a grand spiral shape of several tapering arms- each made up of stars, dust and gas. The Sun is one of those stars in one of the interior spiral arms.In spring the dusty Milky Way Band, which is what we see looking inward towards the neighboring spiral arms or the central hub, is largely away from view. What we see is a relatively clear view of the untold number of galaxies beyond. Cosmologists, which is what astronomers who study the cosmos at large are called, have traced billions of galaxies in a fascinating pattern not unlike a fisherman’s net or spider web. The very fabric of the Universe is so vast we can barely comprehend or explain it. Galaxies are found to be grouped together in immense clusters, and those clusters are associated with one another, linked by gravity.Intriguing astronomers is the revelation that the known mass of the galaxies and their clusters, is far too small to answer for the effects of gravitational forces that are observed. Until they decide what is causing this mysterious extra weight, they refer to the extra mass simply as “dark matter.” As always, we find more questions than answers, which is a wonderful thing. The book is never closed.Looking south on spring evenings, before us is the vast Virgo Galaxy Cluster, so named because much of it is within the constellation Virgo. The Virgo Galaxy Cluster contains about 2,000 member galaxies. It is the nearest galaxy cluster to the Milky Way, approximately 50 million light years away. How far is that? The cluster is about 10 million light years across in its longest dimension. We too easily take these numbers for granted. Light traveling at just over 186,000 miles a second takes 50 million years to reach us at this distance. Each light year is almost 6 trillion miles. Even that’s hard for us to fathom. A few people we hear about have a billion dollars or more. A thousand of these people together would have one trillion bucks. If you spent one dollar a minute it would take you 100 years to spend just $52 million. If you buy a $100,000 house every minute you would have spent $5.2 trillion in 100 years. That’s a lot of houses.Even a small telescope will show you several of these far away outposts. A word of caution: you will NOT see large , detailed and colorful galaxies like you see in photographs. Large telescopes with long exposure photographs reveal incredibly detailed pictures which we use to study and admire, but the view in your eyepiece in your backyard will show little else than a faint, fuzzy spot. You will be able to see the brighter central hub and dimmer surrounding portion, on some of the larger or closer examples. A telescope with an eight inch lens or mirror will start to show spiral structure in a handful that are galactic showpieces. One of these is the fabulous “Whirlpool Galaxy,” M51, located just off the end star of the handle of the Big Dipper. Not far away, another wonderful galaxy in the constellation Coma Berenices, and known as NGC 4565, appears as a thin needle with the bright central hub. The Whirlpool is seen face-on, like you are staring down at a breakfast plate. NGC 4565 is oriented to us “edge-on” as if you held your plate’s edge up in front of your eyes. Don’t drop the pancake.Much closer than the outer galaxies are of course are own stars, and closer yet, the planets. This spring the brilliant planet Jupiter shines in the Virgo constellation, about 12 degrees to the upper right of Virgo’s brightest star, Spica.Early risers (or very late go-to-bedders) can enjoy Venus shining very bright, low in the pre-dawn east-northeastern sky.New Moon is on May 25th. Keep looking up!

— Peter Becker is Managing Editor at The News Eagle in Hawley, PA. Notes are welcome at news@neagle.com. Please mention in what newspaper or web site you read this column.